Steelers stole hidden gem safety who will turn heads at rookie minicamp

The Pittsburgh Steelers have found gems combing through the undrafted free-agent pile in recent years. Last week, they may have done it again with the signing of Iowa safety Sebastian Castro. At 24, Castro is on the older end of the spectrum for rookies, but with age comes wisdom. That may be exactly what the Steelers need in their secondary. 

Three years ago, the Steelers signed an undrafted free agent running back out of Oklahoma State named Jaylen Warren. Last year, they unearthed Beanie Bishop Jr. in the undrafted heap.

This year, Castro could be Pittsburgh’s next sleeper. 

Sebastian Castro is a Mike Tomlin-style grinder

Castro is a master of many domains. He thrived operating the “CASH” position. It was a chimera-like role the Hawkeyes' stout defense has become known for since 2018 that required him to bounce between hybrid slot corner, safety, and linebacker. Playing alongside Cooper DeJean as a junior, Castro replaced Giants fourth-rounder Dane Belton and didn’t skip a beat. As the chimera on Iowa’s defense, he accumulated 61 tackles, defended eight passes, picked off three passes and recorded a sack en route to being named a third-team All-American.

Castro’s numbers regressed in 2024, and then, shockingly, he escaped the draft without hearing his name called. A handful of glaring flaws exist in his film, but a 4.59 40 at the NFL Combine standing at 5-foot-11 and 215 pounds likely sank his stock. However, Tomlin’s preference for grinders on the defensive end who don’t have great physical traits puts Castro in a solid position heading into camp. 

Curiously, those are adjacent to Troy Polamalu’s measurements. But I should emphasize that Castro’s upside isn’t in the ballpark of Polamalu’s. It’s instructive to remember that Polamalu ran a 4.3 40 and was a first-round prospect who matriculated into the Hall of Fame. However, there’s a strand of Polamalu in Castro’s football DNA.

Middling athleticism aside, there’s plenty to love. Castro’s downhill tackling is treacherous. He mugs ball carriers in an alley, and is a compactor in zone coverage crushing receivers in zone. He’s a ballistic missile in the secondary or in the box and at the point of impact compacts and crumples intended targets. Scouts can be wrong, results bear the truth. In two seasons as a starter, he forced five fumbles. 

Tomlin’s defenses have been searching for splash plays from the safety and slot positions. That hard hat element has been missing from Minkah Fitzpatrick’s game for the last two seasons. Cameron Sutton was a bust in his return and Bishop still has kinks to iron out in coverage.

The Steelers currently have four safeties on their roster. Castro would be the fifth and is likely to receive an opportunity to put plenty of his snaps on film during the preseason. Tomlin’s affinity for Iowa defenders in recent years is an extra bonus, but on his own merits Castro has the makings of another undrafted Pittsburgh Steelers heist.